Paper making and fiber liberation – Processes of chemical liberation – recovery or purification... – With non-fiber material added to product
Patent
1996-04-19
1999-04-27
Silverman, Stanley S.
Paper making and fiber liberation
Processes of chemical liberation, recovery or purification...
With non-fiber material added to product
162184, 162263, D21H 2306, D21H 1729
Patent
active
058977449
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a method of manufacturing a paper product containing anionic laminating, coating or sizing agents, said paper product being free from carry-over speck defects in recycle use.
Most paper grades and converted paper products contain plenty of anionic compounds partly stemming from the own extractives of pulp wood and partly from chemicals used in paper manufacture. When the fiber material of paper is reused in broke recycling or repulping of recycle paper, the anionic components tend to become dissolved or dispersed in factory circulation waters. As a result, the dispersed anionic trash material tend to adhere on the paper-manufacturing equipment, wires, drying felts and cylinders, etc., whereby problems arise in the form of reduced production capacity, shutdowns and degradation of product quality. The extent of the trash material problem is in linear proportion to the amount of anionic components in the paper products being recycled. A particularly tough problem in this respect is formed by, e.g., coated print paper grades in which the coats contain abundant amounts of anionic binders such as carboxylated latexes, for instance. Still larger trash material problems are incurred by converted paper grades coated with anionic compounds such as barriers to transmission of moisture vapour or gases, for instance. Also different dispersion, self-adhesive and hot-melt types of adhesives cause problems through accumulation of such trash materials in paper recycling.
A method used in an increasing extent to control the problems caused by trash materials comprises adding such cationic, conventionally polymeric, trash control agents to the paper-making process that are capable of fixing the anionic trash materials to the pulped fibers. The cationic agent is then added to the water-suspended pulp at a suitable point along the paper-making line.
These actions of rectifying the trash material problems which are performed-at the formation end, that is, wet end, of the paper-making process are a most useful solution to the end of locally overcoming the problem situations caused by, e.g., repulping of the broke originating from the plant. With the continuously tightening requirements for increased degree of paper recycling, this approach, however, represents no universally applicable nor sufficient solution; namely, defibering (repulping) facilities must be available for recyclable fiber material irrespective of whether the plant performing the repulping of the recycle fiber has the provision of using an anionic trash control agent at an early stage of the paper-making process or not.
SUMMARY OF INVENTION
It is an object of the present invention to provide a universal solution to the above-described problem. The method according to the invention is based on neutralizing the anionic net charge with a cationic compound so that said cationic compound is added to the ready-formed web after the formation of the web. Then, the product entering the market contains an internal trash control treatment, thus relieving the defibering plant from any trash material control problems imposed by the product.
Accordingly, the present invention comprises the addition of a cationic compound to the web. The application of the compound can be made in a plurality of alternative points along the process line: by spraying the compound to the formed web travelling on the wire or drying felts, applying the compound to the web after the dryer section of the paper machine prior to the application of the coating and sizing furnishes which increase the anionic load (such as, i.e., pigment coating or barrier coating with an anionic dispersion furnish), or alternatively, after the coating and surface treatment steps.
BEST AND VARIOUS EMBODIMENTS FOR CARRYING OUT INVENTION
As regards to the intended function of the invention (that is, recyclability of the paper product), no major difference exists on which side of the web the cationic compound will be applied or whether said compound will possibly
REFERENCES:
patent: 4872951 (1989-10-01), Maliczyszyn et al.
Gottberg Jens-Mikael
Hamunen Antti
Nurmi Kari
Nguyen Dean T.
Raisio Chemicals Oy
Silverman Stanley S.
LandOfFree
Method for controlling speck defects in recycling paper product does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for controlling speck defects in recycling paper product, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for controlling speck defects in recycling paper product will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-683859